Tuesday, December 18, 2012

The pause should not surprise anyone familiar with the current state of climate science. The relative importance of the many causes of the two century-long warming remain uncertain (only since 1950 has anthropogenic CO2 been the largest driver). There are many factors at work: natural cycles, volcanoes, solar cycles, emissions of CO2 and aerosols, land use changes — and feedbacks (eg, warming on atmospheric humidity). Some of these are poorly understood. This makes reliable forecasts difficult, especially to the degree required before re-shaping the world economy.

That’s the import of the pause. The long warming will resume, continue, or end. Climate scientists will analyze its causes and continue to improve their models. But the for today the warming pause should make us pause for thought before taking drastic action. The standard of proof required for public policy must be higher than that for academic study. The unexpected nature of the pause (appearing in the literature only after its appearance in the data), suggests that climate science models might not yet provide a reasonable basis for large-scale public policy action.